Technical Abstract:
During the first 1-7 days of life, both chickens and turkeys show an increased susceptibility to infection by bacteria such as the salmonellae. This increased susceptibilty has been attributed to decreased granulocytic cell function, T cell proliferation, and T cell function. Our laboratory has focused on granulocytic cell function in neonatal chickens and turkeys, specifically heterophil function and its relationship to neonatal susceptibility to Salmonella infection. We have shown that the administration of lymphokines (ILK) isolated from chicken splenic T cells harvested from Salmonella enteritidis (SE) hyperimmunized hens confer protection from SE organ invasion in day-old chicks and that this protection is mediated by the activation and mobilization of heterophils. Previous work in our laboratory has also shown that the ILK also provides protection against SE organ invasion in day-old turkey poults. The present work shows that a transformed SE-immune T cell line produces lymphokines (VILK) which result in the same levels of protection against SE organ invasion as does the ILK and that this protection is also mediated by heterophils which are activated. VILK treated heterophils from day-old turkeys showed significant increases in CD18-dependent adherence, chemotactic activity, phagocytosis of SE, and luminol-dependent chemiluminescence when compared to control heterophils. In addition, the administration of VILK via per os, subcutaneous injection, and intranasal routes is shown to elicit the same levels of protection and heterophil activation as previously shown with an intraperitoneal injection.